docx-js/src/file/paragraph/run/field.ts

import { XmlAttributeComponent, XmlComponent } from "@file/xml-components";

const FieldCharacterType = {
    BEGIN: "begin",
    END: "end",
    SEPARATE: "separate",
} as const;

class FidCharAttrs extends XmlAttributeComponent<{
    readonly type: (typeof FieldCharacterType)[keyof typeof FieldCharacterType];
    readonly dirty?: boolean;
}> {
    protected readonly xmlKeys = { type: "w:fldCharType", dirty: "w:dirty" };
}

export class Begin extends XmlComponent {
    public constructor(dirty?: boolean) {
        super("w:fldChar");
        this.root.push(new FidCharAttrs({ type: FieldCharacterType.BEGIN, dirty }));
    }
}

export class Separate extends XmlComponent {
    public constructor(dirty?: boolean) {
        super("w:fldChar");
        this.root.push(new FidCharAttrs({ type: FieldCharacterType.SEPARATE, dirty }));
    }
}

export class End extends XmlComponent {
    public constructor(dirty?: boolean) {
        super("w:fldChar");
        this.root.push(new FidCharAttrs({ type: FieldCharacterType.END, dirty }));
    }
}